A long-lived Donor-Acceptor fluorescent probe for sequential detection of Cu2+ and biothiols

A new long-lived Donor-Acceptor (D-A) fluorophore based on carbazolyl dicyanobenzene was developed as an ON-OFF-ON multifunctional fluorescent probe 1 for sequential detection of Cu2+ and biothiols (Cys, Hey and GSH). The fluorescence of probe 1 can be significantly and selectively quenched by Cu2+. Meanwhile, the fluorescence lifetime decreased from 2.1 mu s to 18.5 ns. The limit of detection was determined to be 33.6 nM. Upon addition of biothiols (Cys, Hcy and GSH), the generated ensemble 1-Cu2+ displayed a "turn-on" fluorescent response at 555 nm and an obvious recovery in fluorescence lifetime and UV-vis absorption within 1 min. The limit of detection for Cys, Hcy and GSH were calculated by fluorescence titration experiments to be 0.19, 0.21 and 0.29 mu M, respectively. The ensemble 1-Cu2+ was further successfully applied in bioimaging. (C) 2019 Elsevier B.V. All rights reserved.